The present invention relates generally to systems and methods for hot working metals and alloys, and more particularly to a method for selecting process parameters in the design, optimization and control of microstructure in metals and alloys during hot working fabrication processes.
Control of microstructure during hot working of metals and alloys according to conventional methods is done by expensive trial and error techniques because no systematic approach exists for the optimization and control of microstructure in the finished product following hot working.
The invention solves or substantially reduces in critical importance problems with existing hot working processes by providing a method for systematic selection, optimization and control of process parameters for microstructure control in the fabrication of a hot worked metal or alloy product. The invention is characterized by two process stages. In the first stage, microstructure is optimized in the final hot worked product using the kinetics of dynamic microstructural behavior associated with the dominant mode of deformation and the intrinsic hot workability of the material, along with appropriately chosen optimality criteria, to select strain, strain-rate and temperature trajectories to achieve the desired microstructure. The trajectories depend on material selection, are independent of die geometry, and can be used in association with various hot deformation processes with similar material flow pattern. In the second stage, the process for achieving the desired product microstructure characteristics is optimized using a process simulation model to predict process parameters (such as ram velocity profiles, billet temperature and nominal preform and die geometries) which achieve the strain, strain-rate and temperature trajectories calculated in the first stage at specific regions in the workpiece. The invention may be applied to a wide range of process models, including simple slab type models and high fidelity finite element simulation models, and is useful in the optimal design and control of manufacturing processes needed for effectively reducing part cost and improving production efficiency and product quality.
It is therefore a principal object of the invention to provide an improved hot working fabrication method for metals and alloys.
It is another object of the invention to provide a method for selecting process parameters in designing, optimizing and controlling microstructure during hot deformation processes.
It is another object of the invention to provide a method for selecting process parameters for controlling microstructure in manufacturing metal or alloy parts of substantially any size or shape.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.